This invention relates to telephones and, more particularly, to multi-line telephones.
There are known telephone arragements such as multi-line telephones, telephone-based conferencing and computer-based-voice conferencing, which appear to have multi-line capability, but in actuality are only enabled for voice communication to use one line at a time. To this end, multi-line telephones provide a user with a number of call appearances with the ability to talk and listen on any one-call appearance at a given time. Phone-based or computer-based packet-voice conferencing systems enable a user to be a participant in a multi-party call, which provides the user the ability to listen to and talk to all of or a subset of the other participants in the conference call. An important point to note is that in a conference call all the participants belong to the same call or session, which is on one call appearance at the participant""s terminal. Typically, each participant in the conference call is aware that he/she is included in the conference call and has some control over when he/she joins or leaves the call. Additionally, each participant may also have some limited control over which of the active participants he/she can hear. In these prior known arrangements, voice input/output at a terminal is only enabled on any one-call appearance at any given time. However, although multiple call appearances maybe active at a given terminal, the user can only speak and listen to one call appearance at a given time. The other active call appearances are considered to be in a xe2x80x9cheldxe2x80x9d state and are not enabled to engage in voice input/output.
These and other problems and limitations of prior known arrangements are overcome by enabling voice input/output to be simultaneously available on any combination of call appearances at a given time on a given terminal. Consequently, a user may, for example, listen to the voice output of one or more call appearances that are active at the terminal at a given time. Additionally, the user may direct voice input to one or more call appearances that are active at the terminal at a given time. Thus, the user, at any given time, may listen or speak to one or more parties on unrelated calls. Additionally, a user can employ more than one voice input/output device at his/her terminal.
Specifically, the ability to simultaneously use more than one call appearance at a terminal at a given time is realized by separating call control from media routing and input/output control. Thus, the appearance of a call at a terminal is separated from the voice input/output that is required for the call. To this end, a user terminal or resources available to it must have the capability of mixing multiple channels of audio, as well as, the capability of multiplexing/demultiplexing voice inputs and outputs into and from line appearances. Also, each call designated as being active at the user terminal must deliver the media associated with it to the terminal or to the resources available to the terminal.